%0 Journal Article
%T Picoplankton Community Composition by CARD-FISH and Flow Cytometric Techniques: A Preliminary Study in Central Adriatic Sea Water
%A Anita Manti
%A Paola Boi
%A Federica Semprucci
%A Rosaria Cataudella
%A Stefano Papa
%J International Journal of Oceanography
%D 2012
%I Hindawi Publishing Corporation
%R 10.1155/2012/909718
%X Data concerning picoplanktonic community composition and abundance in the Central Adriatic Sea are presented in an effort to improve the knowledge of bacterioplankton and autotrophic picoplankton and their seasonal changes. Flow cytometry analyses revealed the presence of two distinct bacteria populations: HNA and LNA cells. HNA cells showed an explicit correlation with viable and actively respiring cells. The study of viability and activity may increase our knowledge of the part that contributes really to the remineralization and bacterial biomass production. Authotrophic picoplankton abundance, especially picocyanobacteria, was strongly influenced by seasonality, indicating that light availability and water temperature are very important regulating factors. In terms of total carbon biomass, the main contribution came from heterotrophic bacteria with a lower contribution from autotrophic picoplankton. CARD-FISH evidenced, within the Eubacteria domain, the dominance of members of the phyla Alphaproteobacteria, with a strong contribution from SAR11clade, followed by Cytophaga-Flavobacterium and Gammaproteobacteria. The bacterial groups detected contributed differently depending when the sample was taken, suggesting possible seasonal patterns. This study documents for the first time picoplankton community composition in the Central Adriatic Sea using two different approaches, FCM and CARD-FISH, and could provide preliminary data for future studies. 1. Introduction Knowledge of seawater microbial diversity is important in order to understand their community structure and pattern of distribution. In the ocean water column, organisms <200£¿¦Ìm include a variety of taxa: free viruses, autotrophic bacteria (cyanobacteria, which include the group formerly known as prochlorophytes), heterotrophic bacteria, protozoa (flagellates and ciliates), and small metazoans [1] with different morphological, ecological, and physiological characteristics. Autotrophs and heterotrophs constitute two fundamental functional units in ecosystems: the first generally dominate eutrophic systems while heterotrophs generally dominate oligotrophic systems [2, 3]. Among these taxa, autotrophic and heterotrophic picoplankton can play an important role in the functioning of the microbial loop [4], with the former regarded as important templates of assimilable carbon biomass at the base of the microbial food web [5], while the latter acts as both remineralizers of organic carbon and trophic intermediaries within aquatic ecosystems [3, 6]. These represent an important source of food for a
%U http://www.hindawi.com/journals/ijocean/2012/909718/